


Slack Water

by tisfan



Series: Tony Stark Bingo [3]
Category: Captain America (Movies), Iron Man (Movies), Marvel Cinematic Universe, The Avengers (Marvel Movies)
Genre: Body Horror, Cannibalism, Consentacles, Hydra (Marvel), M/M, Mer-eel Tony, Oral Sex, Sort Of, Tentacle Sex, Torture, Violation, close to vore, gimme a break, grotesque bodily violation, mermaid au, non-sexual Hydra Trash Party, octobucky, tony's a fish
Language: English
Status: Completed
Published: 2018-06-03
Updated: 2018-07-04
Packaged: 2019-05-17 12:15:48
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 6
Words: 8,888
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14832092
Author URL: https://archiveofourown.org/users/tisfan/pseuds/tisfan
Summary: In the slack water of Hydra’s tanks, mer-eel Tony tries to help the newest captive survive.





	1. Ripples

**Author's Note:**

  * For [beir](https://archiveofourown.org/users/beir/gifts).



> For the Tony Stark Bingo, square R1: Merpeople

**Notes for the Chapter:**

> Now with art from [Monobuu](https://archiveofourown.org/users/monobuu/pseuds/monobuu)

Tony crouched low, near the _outflow pipe_.

There was thick, hard water -- what the man-things called _plastic_ \-- between him and the supply of dubiously fresher water. He couldn’t reach the actual pipe, a black and rounded thing that fed oxygen into his cramped space. They’d made that mistake once, and he’d nearly escaped, getting his fingers on that material and fashioning a weapon from the _metal_. Now there was a plastic casing around the pipe, and even less fresh water got to him than before.

It was a struggle to breathe.

Tony knew the fresher water was near the pipe, and even where he could feel the faintest current, each flex of his gills was harder than the one before.

If it weren’t for the food that came, at irregular intervals, Tony might have thought that the man-things had forgotten him. He had long since proven intractable to their training, no matter how much they hurt him. And they had been creative in the amount of pain they put him through.

Tony wondered if the lack of oxygen was a new phase of hurting.

It made him weary, unable to fight back.

But they hadn’t come and made their incomprehensible demands of him, hadn’t come to scrape his skin, to peel at his scales, to burn him, or freeze him.

He was getting thinner, weaker.

If they were going to demand something of him, now, he might give in.

Almost.

He was so _tired_.

The portal opened, letting in a few of the man-things. They were making noise, dragging something between them that struggled weakly. It was wrapped in wet blankets. Long arms dragged on the ground, the ends twitching. One of the man things stomped on the very end, causing the struggling thing to cry, pitiful and full of agony.

One of the man-things jabbered, pointing at… no, not at Tony, but at the empty space next to him. They climbed up, and dumped the struggling thing into the tank. Not Tony’s tank, not his space of slack water, but the next one over, with a thick wall of the plastic separating them. Tony moved away from the outtake pipe, curious. Someone else?

He’d been alone for so long. He couldn’t help it, his hands came up to touch the chill plastic between them.

The other person struggled with the blankets, sank straight down to the bottom of the tank and just lay there, the blankets still over them. Tony struck the plastic between them. _Wake up, get up, get up._

The other twitched at the vibrations. _Come on, you can do it, wake up. Lemme see you._

Thick arms emerged. One was too short, much too short, waving a stump around. Fresh blood stained the already murky water. Another arm tugged at the blankets until the other lay, uncovered, still struggling. The final shift, and Tony’s eyes widened.

_What did they do to you?_

There was a man-thing attached to the other, silvery bright and metal. It moved as if the other had control over it, like it was his own arm, but it was horrible. Sinister, somehow.

Tony recoiled, was back against the far side of his tank, his ion channels flooding with salt as his organs tensed to produce the electrical shock that was his main defense.

Whatever Tony’s feelings were about the other’s manthing, he was, at least, not attached to it. The other held out both hands, screamed. Twisted the silvery limb, screamed again. Slammed himself into the plastic sides of the tank in a panic, trying to flee a thing that couldn’t be left behind.

Tony crept forward until he was back at the adjoining wall.

 _Hey. Hey, hey, there. Hey, hey._ Tony struck the plastic again, and the other crashed to a halt. He reached for Tony, seemed startled when he couldn’t get through the plastic.

 _What?_ The other’s accent was strange, rich and slow. Different waters. _Who are you? Are you with_ them _?_

_The man-things? No. I’m Tony. They captured me. Do you have a name?_

Four coiled tentacles pounded against the plastic, one normal hand. Thud, thud, thud. The beat was syncopated, sending shivers through Tony’s entire body. _Hey, don’t do that._

The silvery hand came up. The other slammed that metal hand into the plastic, driving so hard from the shoulder that his entire body was forced backward from the impact. The water in Tony’s tank rippled from the force.

 _Neptune! Don’t do that, don’t, don’t, don’t…_ Tony swam around in a panic, his organs shifting and sputtering as he started building a charge. All the brilliant blue patches on his scales lit up, shining a dim light between them. _They’ll hurt you, don’t do that._

Tony was too late.

The manthings were there with their sharp sticks and nets, prodding the other away from the plastic, cutting open gashes on his chest, his arms, along the thick, rubbery part of his body. The net came down, and the crackle of electricity echoed in Tony’s chest.

The other collapsed, trying to flatten himself, screaming. Bubbles issued from his mouth, then stained with blood. Ink trickled from his glands, not enough to hide him, even if there was anyplace in that wretched slack water to hide. The other went through a rapid series of color changes, but it was no good, all the defenses of Neptune’s children did nothing against the manthings.

Tony watched. There was nothing else he could do. Even if he drew attention to himself, they wouldn’t leave the other alone, they wouldn’t take his bait, hurt him instead. They would just both be hurt. _Leave him alone._

By the time the manthings tired of hurting the other for the sake of hurting him, Tony was slumped against the plastic wall, hand reaching, sobbing for the other’s pain. _I’m sorry, I’m sorry._

Finally, the manthings left, and Tony waited until the other dragged himself up again.

He pulled himself over until he was laying exactly opposite of Tony, one hand on the plastic, his real hand. Tony overlayed his hand, palm to palm, giving as much comfort as he could. _I’m Tony._

_Tony._

_Yeah, that’s right. I’m Tony. Who are you?_

The other looked at him, eyes as blue as Tony’s luminescence. _Don’t know. Don’t know. Don’t have a name. Tony. Tony._

The other leaned his head against the plastic, shivering all over.

 _Aw, Starfish, I’m sorry._ Tony ached for the other’s pain, his fear.

_Starfish?_

_Well, I have to call you something, if we’re going to be friends, right? I can’t just say Hey you, all the time, right? You’ve got a little star on your shoulder, there. It’s pretty._

The other stared at the star, his fingers digging into the flesh around the metal arm, as if he could rip it off. He didn’t succeed in doing anything more than making himself whimper in pain. _Friends?_

Tony gave Starfish a smile. _Of course. The enemy of my enemy is my friend. Hydra… hydra’s our enemy._

_I hate them._

_Yeah, me too, Starfish._

_I’m going to kill them all._

Privately, Tony thought it was unlikely. That hatred would carry Starfish through for a while. Hatred carried Tony through for a while. But it would end with weariness. _It’ll be okay. We’ll get out of here, together._ That was a lie, too, but what other comfort could Tony offer.

_Tony._

_Yeah, Starfish?_

_Friends?_

_Yes._

 


	2. Gyre

**Summary for the Chapter:**

> Starfish doesn’t remember who he is, but he’s going to kill every last member of Hydra for what they’ve done to him

**Notes for the Chapter:**

> This chapter is very DARK. Skip to the bottom notes for more details
> 
> And more art from monobuu because monobuu is awesome...

_He chased after the taste in the water. He’d known something, he was reaching -- down? The face, horrified for just an instant, before he was peeled away._ Steve!

He jerked himself awake, away from the dream, away from a name, someone’s name. Not his. He didn’t know his name. Starfish was what the other had called him, joking around that Tony couldn’t just say hey you all the time. As if there were anyone here to be called.

Starfish did a lap around the tank, pressing his face to the clear plastic, checking the walls. He didn’t know what he was looking for until he did. There was a simple white square thing in the upper corner of one of the rooms.

_Tony. Tony wake up._

The daggerfish, Tony, had taken to resting near his intake pipe, where the water was nominally fresher. Starfish had seen how hard Tony’s gills were working. The mans were poisoning him with bad water, a little at a time, making him weaker.

_What is it?_

_Need you to do something for me._

Tony swam closer to their joining wall. _What can I do?_ He had a reason to sound skeptical, but more fish than just Tony had underestimated octomers to their vast dismay, later.

 _I need recon_ , Starfish told him. _Need you to run a distraction mission for me. Go to the far side of your tank._ Starfish considered the box again. _Bang on the walls or something. Get their attention. They may come and hurt you. I’m sorry._

He needed the information, but he couldn’t both distract and observe at the same time.

Tony nodded. He laid his hand against the barrier and Starfish covered it with his own. It seemed to give the other mer some comfort. He darted to the far side of the tank, then, fingers exploring the corner, as if searching for a weakness in the binding. Starfish kept his eyes on the square, waiting.

A brilliant flash of light illuminated the tank for just a moment; Tony had discharged. Based on the vibrations, a partial, warning spark. Starfish had known a few of the mer-eels before, they had several different blasts they could issue; from a warn-away to enough of a blast to cause distress to something as large as a shark, disrupting its heart. Escape, weapon, a method for hunting.

He would be an Asset, if Starfish could get a good plan going.

For a long moment, nothing happened. Tony discharged again, then started pushing at the corner.

The box swiveled on its peg.

 _You can’t hide from me._ Starfish would have purred in triumph, but he never knew how much the mans could hear him. Besides, he had a job to do. There wasn’t going to be much time to do it, either.

The mans came into the room with their spears and their implements and their nets, banging at the sides of the tank. While they were occupied with hurting Tony, and Starfish tried not to listen, not to hear, the horrible sounds coming from the other tank, Starfish raced up to the top of his tank. The square still was looking at Tony’s tank. Starfish had not yet figured out how the square saw, how it reported to its masters, only knew that it _did_.

Starfish darted around the edges of the tank until he found the outflow piping. Stupid mans. He squeezed, keeping the mansthing arm well away from the hole he’d found. There was no way he could get that thing anywhere, and if he squeezed that part of himself, he’d only hurt himself, and possibly alert the mans to what he was doing.

Check of the square again. It hadn’t moved.

Starfish spit, a siphon of water and mixed with his ink. It splattered right where he wanted it, coating the mechanism that held the square to the wall. Ink wasn’t really corrosive to underwater things, a camouflage or distraction, but to the mansthings, it was sticky. Slowly, if they didn’t notice it, it would damage the tiny parts that made up the mansthing.

Mission accomplished, Starfish let himself sink down to the bottom of his tank, bearing witness to the terrible things the mans were doing to Tony.

Aching for the other mer.

He knew how the sticks and pain felt, he knew the terrible things that the mans could inflict, for no reason, for nothing. Mans and their wars.

When they finally left, Tony was left keening, all his electrical bladders discharged, dull and black and limp and lifeless.

_Tony?_

_...ow._

_I know, I know, I’m sorry._

Tony raised his head and dragged himself across the floor, unable to even get enough energy to swim. He got to the wall between them. _Did you get what you needed?_

_Yes._

_At least there’s that._ Tony managed to press his fingers to the barrier, and Starfish covered them with his own.

_How long will it take you to recharge your shock?_

Tony waggled his hand back and forth, a mans gesture. _A cycle, little longer. Hard to tell when the sun passes._

_Any way to speed that up?_

_More food. There’s never enough of it._

Starfish nodded. _You can have mine._ They’d only get one chance at this, before the mans realized what Starfish could do.

Tony didn’t bother to protest that there was no way Starfish could share a feeding between the barrier. He was too hurt, too tired. Starfish let himself sink down, until they were both laying on the bottom, barely across from each other.

His wounded arm ached, the mansthing attached to him pinged and vibrated.

_You killed one of them. It wasn’t a question._

_Not today. How--_

_I speak the mansthing. One told the other not to hold the stick on you, if you discharged._

Tony nodded. _When I first came, I dumped a whole charge into one. Their hearts are weak. I thought they would kill me for it._ He waved one hand around, indicating how well that plan had worked out.

_They want to make you a weapon. Against the other mans._

_They won’t._ Tony promised it, grimly.

Starfish looked at the manthings’ arm, attached to him in such a way that he could never remove it. _Don’t bet on it._

_What happened to you?_

Starfish closed his eyes. Behind his eyelids, the scene danced before him again. _Lost this--_ he waggled the mansthing back and forth-- _when they took me. They put this in its place._

_And that?_

Starfish opened his eyes. His other arm, the bleeding a sluggish trickle, was a mere stump. If he was still in deep water, he would have needed a cave to hide, predators would be drawn to his scent. _They cut it off. To teach me not to try to remove--_

He wrapped two arms around the mansthing, demonstrating what he’d been trying to do, wrench the mansthing out of his own flesh. It felt… wrong. Like a tumor set inside his body, a malevolent, thinking _thing_. He still wanted to remove it, stop whatever it was doing to him, the poison that was seeping into his body from the device. But what they had done… what they had…

 _Starfish_!

Tony was thumping on the divide; not hard, just enough to rouse him from his panic.

Starfish laid his hand against the divide. Wanting the comfort that Tony could give him. Needing it.

_What happened?_

Starfish shook his head. _They_ ate _it. They made me watch._

__

**Notes for the Chapter:**

> Mentions of torture, mentions of cannibalism (In that Hydra torturers eat part of Bucky that they cut off.) grotesque bodily violation, body horror, Hydra Trash Party (non-sexual)


	3. Phytotelma

**Summary for the Chapter:**

> For Square R4 -- Angst

**Notes for the Chapter:**

> more art, Bucky and Tony cuddling, by monobuu

Tony was pretty sure he never wanted to move again. He hurt, so bad. He lay on the floor in his tank and wished he could just die.

_Hey. Hey there. Come on, food’s here._

_Food_. Tony expelled a jet of water. He didn’t care about food. He barely maintained enough sense to be surprised that the manthings brought food. Surely, in the wake of their punishment, they would withhold food.

There wasn’t anything to hunt, in these still, lifeless waters.

_Go away._

Starfish banged on the barrier between them. _Come on, I need you._

No more, not today. Leave me alone to die.

I won’t. I won’t. Just look up. Come on, Tony.

Everything hurt. He ached. He couldn’t breathe. He managed to push himself up, a little. Heaved a few breaths, like rocks over his gills. Inflated his swim bladder and rolled over listlessly. Another few puffs and maybe he could go belly up to the surface.

 _I can’t see. How big is the opening on your outflow pipe? This big?_ Starfish made a circle with one of his arms, pushing it flat against the barrier.

An interesting puzzle. Tony floated, considering it. He traced the circle a few times with one finger, then eyed the piping. _Little bigger, I think._ Spacial relations. His father had taught him. The ability to visualize, rotate, imagine. How an object was placed, in relation to another object. Everything to do with swimming fast, with moving between obstacles, will I fit there, can I dodge that?

Great. Rest, Tony. I’ll bring you some food.

Tony didn’t even bother to protest that it wasn’t possible.

There was food, dead food, but food, on the surface. Tony could smell it, but he couldn’t care enough to swim up to get it. Ug. Just the thought of moving made him want to regurgitate.

Tony rolled back over to express that to Starfish.

The octomer was _gone!_

Tony struggled to right himself in the water, confused. A whirl of emotions so vast he couldn’t even tell one from the other, swirled through him.

And then there was a clanking, scraping noise and Starfish yanked himself out of the outflow pipe by those metal fingers. He struggled, trying to bend enough to squeeze through the narrow gap between the pipe and the plastic sleeve the manthings had secured it behind.

_What are you doing?_

_Bringing you food._ Starfish said it like it was only natural. He squirmed, writhed and then popped back into a more normal shape. Tony’s head hurt, watching it.

The octomer came closer and if Tony hadn’t been so exhausted, he might have darted away from instinct.

 _Awww. Look at you. Here, you eat this, and I’ll take care of this._ The octomer used one arm to poke a succulent clam at him, the meat tender and sweet.

Tony ate, and while he was chewing, Starfish coiled around him, poking at Tony’s wounds, and then licking them, his tongue darting out and coating Tony’s skin with some sort of thick, viscous goop that clung to him and made his skin go numb. Relief from pain was almost agonizing for a long moment before it eased.

 _What--_ Tony did not like the feeling that the octomer might be sizing him up for a better meal.

Starfish nuzzled at Tony’s throat, licking at another spot. _It’s good. Hurts less?_

 _Hurts less,_ Tony agreed.

 _Good. Stay still, this will hurt._ Starfish licked again, a spot on the back of Tony’s arm, near his shoulder, then he bit, bit him, deep and painful.

Tony jerked, salt trying to flood his organs but he was too tired to raise so much as a stinging warning, and he shrieked his dismay, he knew, he knew, he couldn’t trust. _Ow! Ow! Ow, let me go, ow!_

Starfish spit something out, a little--

Tony lunged for it, metal and glittering and… _what is this?_ Had that been _inside_ him? Tony shuddered all over, disgusted.

_Tracker. They put it in you so they can follow you._

Tony let the little thing go, as if it had grown barbs. He eyed it warily, but it only lay there, on the floor of the tank.

_Eat, eat. You need your strength._

Starfish fed him, and when Tony was finished eating the bits that Starfish had brought through with him, the octomer swam up and fetched Tony’s food down as well.

Not hurting so much, pleasantly full, Tony stretched. The octomer wrapped around him, limbs twining around Tony’s body, holding him fast. _What are you doing?_

 _Cuddling,_ Starfish said. _Don’t shock me. You need that. After. Sleep. I’ll wake you._  

 _Cuddling. Okay._ Tony didn’t know what the word meant, but he felt comfortable and safe, wrapped up in Starfish’s arms. Safe. He hadn’t felt safe in a long, long time. Tony tucked his face against the curve of Starfish’s throat and slept.

_Wake now, Tidepool._

Starfish pressed his mouth against Tony’s mouth, licked at his lip.

Tony jerked backward, startled. _You are so_ weird _. But I like you._

 _It’s a kiss. It’s nice._ Starfish told him, pouting. _How are you feeling? All charged up?_

Tony considered his organs, the salt that flowed between them. He nodded. _Think so._

 _Great! Come here, come here, come here…_ Starfish swam up to the very top of the tank. _Need you to zap this, hard as you can._

_It’s plastic. The manthings make them. I can’t hurt it, it’s not alive._

_It’s a motor. It’s spinny, inside. Cut me up to bits. But if you zap it, it’ll stop working. I can get through._

_And then what?_

_We get out of here._

Tony considered the tank, considered Starfish and his ability to squish through the outtake pipe. Considered the distance from the tank to the manthings portal. Even if there were water on the other side, Tony couldn’t breathe without water. He would die on the way. But Starfish was an octomer. He could breathe air. For a while. He could get out. He could get away. And maybe, maybe, he could get the top of the tank open. Tony would die, but at least he would die when he wanted. His choice.

_Back away._

Tony squeezed his organs, building the charge. Thought of all the times the manthings had hurt him. Remembered them hurting Starfish and how the octomer had screamed. All the terrible and hateful things that had been done to them both. The ones who had been here before, and died, and Tony didn’t even remember their names. The charge built and built until he was aching with holding it in.

He reached out, touched the plastic -- motor, Starfish had called it -- and discharged.

The thing died with a puff of black cloud and an acrid, unpleasant smell.

Perfect, that was wonderful. Starfish grinned, swam up to Tony and threw his arm around Tony’s neck, bringing him in for another _kiss_.

Maybe it was nice. Tony let him, moving his mouth curiously. Starfish tasted sweet and there was some heat and comfort to putting their mouths together like that. _It’s still weird._ Tony laughed, pushing him away playfully.

 _You like it._ Starfish inspected the motor. _Okay. Out._ He squished himself down, flat and wriggly and Tony had to not watch, because ug, that made him uncomfortable.

A few minutes later, Starfish dropped out of the other side, into the air. He splatted onto the floor, slithered like a true-eel. (Tony was only called an electric eel, he was, in fact, a breed of daggerfish and not an eel at all.)

_Wait. Where are you going?_

Starfish paused at the portal, pointed with several of his arms.

_Don’t leave me. Don’t leave me here!_

_You’ll die without water!_

_Don’t you leave me here!_ Tony banged on the wall, frantic. _Take me with you. Please, please, don’t leave me here._

Starfish shook his head, pointed again.

And then he was gone.

He was gone.

He left.

Tony sank slowly to the floor of his tank. When his hands touched the plastic there, he screamed, furious, grieving.

_He left me._

_He left me behind._  


	4. Pelagic

**Notes for the Chapter:**

> For Tony Stark Bingo S5 - Seeing Red
> 
> more arts from monobuu. this didn't actually happen (exactly) in the fic, but it's hilarious and I love it.

Starfish didn’t have any time; he could already feel the vibrations in the floor of manthings, at least two, headed their way. He let himself out of the cavern with the tanks, scurried up the wall to the ceiling and shifted color. Just before the manthings touched the portal that would take them to a wailing, crying Tony, Starfish dropped onto one, wrapping two arms around the thing’s neck and squeezing.

He slid another arm down, grasping at the tools of the mansthing, that they wore around their middle.

**Gun**

The thing in his arm, the mansthing that wasn’t part of him provided the word, slid information into Starfish’s brain of how it worked. Too loud. Another grab and he pulled out a sharp stick --

**Blade**

\-- whatever.

Wrapped another arm around the second mansthing’s chest, pulled it in close. The mansthing opened its mouth to make noise, to call others. Starfish shoved his hand into the mansthing’s mouth, blocking the sound, then yelped, as the mansthing bit him. Its teeth weren’t sharp, but the bite tore his skin, crushed one finger. It hurt.

_No. No, you don’t get to eat any more of me._

Monsters. They were all monsters, horrible creatures that died in the water and took from the seas without regard.

Starfish used the sharp stick to stab it, over and over. In its face, in its chest, in its belly until it stopped moving.

It bled the same color that Starfish bled.

The other quit struggling, stopped futilely tearing at Starfish’s thick skin, stopped trying to pry the coils from around its throat.

Starfish stabbed that one, too, just in case.

When they were both dead, Starfish dragged them aside, into another room, full of incomprehensible stuff, the stuff and tools and things of mansthings. The flat things, full of kelps that held and bound him, tools of pain. Tools that cut and bit, that--

Starfish turned away. Even if there were things there that he could use, he couldn’t bring himself to touch them.

A smaller cave, filled with sweet water. Starfish slithered into it, wetting his skin. It was clean, exactly the right level of salt. He curled into the bottom of the tank, breathing in the water. When he climbed out again, sated and feeling much better, the tank rolled away from him. It had… it had manthings on it.

 **Wheels.** The dark voice in his head seemed almost contemptuous, like Starfish was a fry, for not knowing the words of the mansthings. Monsters, beasts, cruel for the sake of cruelty, Starfish knew some of their words, but they were ugly words. Still, the wheeled water that was a thing worth considering. He used yet another arm to drag it along behind him.

The next cavern, past the -- **Lab** \-- (shut up, shut up, leave me alone!) was full of other, useless mansthings.

**Computers.**

Soft whirs and beeps. The air was cool and dry, uncomfortable against Starfish’s skin. He dragged the mansthing over the floor, found small caverns and stuffed them in. He took the tools of the mansthing--

**keycard.**

_Stop it, stop it, stop it._ Starfish pounded himself in the head, the voice was aggravating and insistent and it didn’t belong to him. He didn’t want it.

He stretched out his arms, yanked at the tools that the mansthing carried until Starfish had taken everything he thought he might need. Two other arms were exploring, making sure this cavern was safe, at least for the moment--

“--Winter soldier project,” a voice boomed. Starfish screeched, turned colors to blend, seeking--

**computer.**

“--is a creature apparently synthesized by the biological pairing of two or more dissimilar living beings into a new, complete form displaying attributes of its components. Residents of deep sea, but adaptable to most climes, chimera are resilient in body. A fragile mental state renders many of the creatures unsuitable for combat --see files Mer001 through Mer105, but several subspecies, as described below, have potential to reach biological weapon stages. Chimeric research has seen very few significant strides and has been described as a science built upon countless dead ends and false starts. The creatures are little more than simple animals, but with proper application of conditioning programs, they can be--”

Starfish drew closer to the computer, head tilted as images flashed.

“--subject Mer107, self-identifies as ‘Bucky’, has been fitted with one of several intended prosthetics, designed for combat applications--”

_Bucky._

Starfish leaned even closer, until his nose touched the little tank. Pictures flashed, and he knew himself, screaming as the manthings cut at him, struggling, struggling. Shocks and pain. He mewled, backed away from pain remembered. They had hurt him, hurt him until he gave them his name, and then they’d hurt him again until he’d forgotten it.

**Conditioning.**

_Leave me alone._

“--subject Mer04, not capable of speech. Training has proved ineffective. Continue to modification inserts.” That was Tony, his Tony. A device, glowing and blue and soft. Pretty, like the bioluminescent runners along Tony’s tail. “--rc-reactor almost ready, implantation to begin--”

They were going to put that thing, that soft, pretty thing, on his Tony. If they meant to do it, it was no good thing. Bucky didn’t understand it, that the device, once it touched Tony’s skin, would burrow in, wrap itself around Tony’s heart, would spin its tendrils throughout Tony’s body. To do _what_?

**Compliance and control.**

There were voices then, in the connecting cavern, shouts, exclamations. One of the mansthing’s tiny stars lit, red and hostile, swirling and blinking.

The portal to the tank cavern slammed open.

 _Tony_!

Bucky tightened his hold on the weapons. Dragged the wheeled waters behind him. The arm, the mansthing arm, grabbed for the **gun** , moved itself as if it knew what it was doing with the tool. Bucky let it. He slithered as fast as he could, coils moving him light and easy across the floor, and the tank of water followed behind him, a little heavy, but Bucky could manage. The portal to the tanks was open, there were mansthings in there, threatening his Tony, his! With sharp sticks and guns, demanding answers that Tony couldn’t possibly give them.

They hurt, just to hurt. They caused harm just for the sake of cruelty.

Bucky raised the gun, steady. The metal fingers pulled back.

The thing exploded in his hand, louder than anything Bucky had ever heard in his life. He slammed the end of one tentacle, the fingers of his flesh hand, into his ears and screamed.

The metal arm didn’t hesitate.

Or stop.

**Bang!**

**Bang!**

Moved a little, squeezed again.

The mansthings were screaming, four dead, five dead. Six…

One of them fired its own gun.

The tank that contained his Tony exploded.

Water gushed from the glass like a wound, spilling everywhere. The mansthings fell, were scattered.

The metal arm kept squeezing the life out of them until the gun in its hand stopped making sounds. He threw it aside, ready to go to war with sharp sticks and his teeth if he had to, but there were none left to stand against him.

The water swirled and eddied and flowed away.

Tony was struggling, reaching for the water as if he could hold it, gills flapping uselessly.

_Starfish!_

I come, I--

But it hadn’t been a plea, had it? Tony was trying to tell him--

A slice of pain across his back, a rush of hot blood. Bucky turned, arms grabbing everything until the mansthing was suspended, stretched out like the starfish that Tony called Bucky. They are cruel, for the sake of cruelty.

Bucky ripped the mansthing into pieces and threw the pieces aside.

Tony…

Tony wasn’t moving. He wasn’t arching and falling and splashing uselessly in the puddles.

_Tony, Tony, no!_

Bucky scurried across the wet floor, faster than he’d ever moved before. He scooped up the daggerfish, pulling him close. _I’ve got you, I’ve got you._

There was no time, and Bucky dropped Tony into the portable tank.

The daggerfish sunk straight to the bottom and didn’t move.

_No, Tony!_

Bucky beat on the glass, tried to wake him up. _Tony. Tony, please, please don’t die, I was as fast as I could be, don’t die, don’t die on me, please…. TONY._

Tony stirred, made a soft, sad sound. _Just five more minutes. I'm sleepy._

 _Tony!_ Bucky crawled into the water, wrapping his arms around the daggerfish, cuddling close. _Tony, you’re alive._

 _More cuddles?_ Tony patted Bucky’s shoulder with weak fingers. _More kisses?_

 _All the kisses you want._  


	5. Tsunami

**Notes for the Chapter:**

> for Tony Stark Bingo, Square K4: mates

Tony didn’t feel so good.

There was water all around him -- and Starfish, too, pulling him into one of those multi-limbed cuddles, his face pressed against Starfish’s chest -- but it was bad water. He couldn’t breathe right. The water was too warm, too full of rich oxygen and it was making him sick.

_I don’t feel so good._

Starfish nodded. Or Tony thought he did. It was hard to tell, with Starfish’s arms all over him, and squashing him. That felt nice, safe. Comforting. But it also made it difficult to move.

_You have water shock._

Tony didn’t know what that meant. He wasn’t sure he cared. He just wanted to lay there, safe in Starfish’s arms and rest.

_We can’t, I’m sorry. We need to go before more mansthings come._

Tony opened one eye, squirmed around a little until he could glare up into Starfish’s face. _I don’t want to go anywhere. Sleep now._

Starfish unwound himself. _It’s all right. I’ll take care of everything. Take care of you. Get you out of here._ Starfish exited the tank, splatting down on the floor. With one arm, gripped the tank and started dragging it across the manthings cavern.

_No out. Sleep._

One of Starfish’s arms wrapped gently around Tony’s wrist, a squeeze of comfort. Tony let himself drift off, rocking back and forth as the tank moved in sharp jerks, a few feet at a time. Sometimes Starfish made noise, as he moved things out of their path -- the bodies of manthings, their strange and unknowable devices, opened portals -- and sometimes he stopped to slither into the tank again, wrapped himself around Tony like a clam making a pearl. _Tony. Tony wake up and kiss me._

Tony decided he didn’t need his eyes open for that, but the movement soothed Starfish’s worries, and he would breathe for a while, before dragging the tank further.

Water sloshed out of the tank, and Tony woke up enough to look. Starfish was dragging, using all of his arms, stretched out obscenely, him up an incline, a few precious inches at a time. _You weigh a ton,_ he complained.

_Had a big breakfast._

The tank slipped backward a few inches and more water spilled out. Tony squeaked and pulled himself to the bottom of the tank. He stared at the cavern floor, dangerous and ugly and empty of water. Tony had never been outside the water for more than a second or two, and if he never did it again, never tried to pass that burning nothingness over his gills, never felt the entire world smothering him, weighing him down--

Tony’s chest ached from sucking water, his heart was beating too fast. Salt flooded his organs, but he didn’t have anything to shock, there was no danger, no real danger, just what was in his head, pointless and pathetic. Tony whimpered and squashed himself further into the water, until his scales were resting on the bottom.

Starfish hauled the tank the rest of the way up the incline, a bit beyond it, then was back in the water, aggressively petting Tony’s hair, his back, his arms. _You’re okay. I’m not going to let anything bad happen to you. We’re going to get out of here._

It soothed the panic, being cradled in Starfish’s arms. _Why?_

_Why?_

_Why are you-- this… all of this. I don’t understand._

_I am helping you because this is a terrible place. And no mer should ever be in this place. I am helping, right? Helping you?_ Starfish was even clingier, the little suckers biting into Tony’s skin. It didn’t hurt, it felt good, but he had to pull one arm off to move his head, and the popping noises as the suckers let go were funny and they left little marks on his skin.

 _Of course you’re helping_. Because that was true. There was no way Tony would be able to get out of this place on his own, he was trapped by his own nature even as much as the mansthings with their ability to survive in the empty nothingness outside the water. _For what, kisses?_

 _All the kisses._ Starfish covered Tony’s face with them, his neck, down his shoulders. _I’m going to get you out of here, and then I’m going to keep you. My interesting mer-eel, my brave, strong, clever Tony. Mine. My mate._

 _That is absolutely the worst proposal I’ve ever heard._ Tony sighed, looking down at his skin where the little bruises marked him. _I don’t even know your name._

_It’s Bucky. I remembered it. So, now will you be my mate?_

_That’s not much better. Bucky._ Bucky. Tony contemplated the new name. It wasn’t quite as sweet at Starfish, but it was good enough. Strong. Bucky would be a good mate; he was smart, he knew the ways of the manthings. He was dedicated, loyal.

 _Have you heard so many proposals?_ Bucky sulked.

Tony made a face, baring his teeth in something that wasn’t quite a smile. _A few. Before I was taken._ More than a few, really. The Starks were a strong breed, his caverns in the ocean were vast and well protected. He was a good provider. _What if I keep you, instead?_

Bucky considered that a moment. _You can do that._

Tony drew Bucky in for another kiss. _My mate. Heart and blood._

 _Mine. Mine mine mine._ Bucky kissed him again, all over his face. _We’re going now._

Bucky climbed out again, continued. Sometimes he would come to the tank and kiss Tony and suck more water -- Bucky could live outside the water, but not for terrible long. He would get dried out and tired. Sometimes he left for a few minutes, to scout ahead. He grumbled quite a lot when they had to backtrack, something about _stairs_ , which Tony didn’t understand even when Bucky tried to explain it to him.

Not far now.

Good. Tony was starting to get more and more uncomfortable from rocking back and forth in this tiny tank, and the oxygen inside was getting stale. He needed to breathe. He needed to swim. He needed--

A portal slammed open and a mansthing strode in. He was shorter than most mansthings, and instead of a shell on its head, or hair -- Tony had seen both. So weird that the mansthings had hair, just like mers did. What did mansthings need with hair? -- this one had only a bald, pale skull with fringe around it.

Behind it, came another, its head grotesque and red and like a dead thing. A dead thing that walked. Tony started shrieking in terror, they were gross, they were terrifying.

They didn’t hold any weapons that Tony could see, no sharp sticks or rock flingers, but they were terrifying, nonetheless.

Salt flooded through Tony’s organs, and he banked it away, concentrating on his fear, on his anger, on his hope for a better and new future.

“Zhelaniye,” the pale on said, his face showing his teeth. He rubbed his hands together and it made a dull, hissing sound, like a snake in the water. Tony shuddered. He never understood the mansthings words, but these were even worse. He didn’t know what they were, or what they meant.

Bucky clasped many arms around his head and screamed. The word was hurting him, somehow. Tony didn’t understand.

_Bucky!_

“Zhavyy,” the pale thing continued. Tony swam back and forth in the little tank, desperate to do something. Something was terribly, terribly wrong and he didn’t understand it.

_Tony, get away, get away from me! You have to get away. He--_

“Semnadtsat'.”

_I won’t leave you!_

“Rassvet.”

_I’ll hurt you, you have to get away--_

_And where am I going to go?_ Tony scrunched himself all the way up at the end of the tank and slammed forward, striking the plastics with all the strength in him. The tank scooted across the cavern floor, maybe a few feet. Tony did it again, and again.

Bucky kept screaming, his words disintegrating into nothingness, until all there was was pain. Agony. His mate was _suffering_.

His mate was _scared_.

Bucky had helped Tony. Tony was going to help Bucky. Water slopped out of the tank with each impact. He had to hurry. The mansthings weren’t paying any attention to him, helpless and contained as they thought he was.

He pushed the tank another few feet, despite the ache in his arms from the impact, despite how fear squeezed at his chest. Despite how ugly and terrifying the mansthings were. No more, no more!

“Pech'.”

Only a few more inches.

“Devyat'.”

Close enough. Whatever was happening was happening faster than Tony knew how to handle it. He shoved, one last time, then leaped, grabbing onto the pale-faced mansthing with one hand. As soon as his fingers touched that dry, unpleasant flesh, Tony ignited all his organs in a single, heart-stopping shock.

The pale mansthing didn’t even have time to scream. His features crisped and seared, his mouth gaped open and ugly.

Tony fell to the dry ground, gasping for water that wasn’t there, and watched his enemy die. _You won’t harm me, or mine, ever again._

The spell of pain and fear that was tearing Bucky apart ceased with the same suddenness as the death of the pale thing. He leaped, all arms reaching out for the red skulled monster, wrapped his arms around tight on the narrow throat and squeezed. More arms, wrapping the creature’s limbs. The red thing staggered back, trying to rip Bucky’s arms free, trying to speak its dangerous and ugly words, but Bucky kept squeezing.

Tony gagged on the hot nothingness, dragged himself back toward the tank. Oxygen. He needed oxygen.

Bucky made a loud, terrifying sound, a scream of anger, and the red mansthing fell to the ground in two pieces, head rolling and fetching up at the base of the tank. Tony made a face, but he was in too much pain to care much; he used the skull to climb, grabbing the edge of the tank, just a little help in this too heavy, too dry place.

With a splash, and a heave of his gills, Tony fell back into the tank and lay at the very bottom of the class, sucking in as much oxygen as he could get.

A moment later, Bucky’s head ducked into the water. _Tony?_

 _I’m okay, I’m okay._ It wasn’t that much of a stretch of the truth, was it? He was alive, he wasn’t hurt. He was just very tired.

_You helped me._

_That’s what mates do._ Tony reached out one hand and touched Bucky’s face. His mate. His… starfish.

Tony closed his eyes and slept.


	6. Shoals

**Summary for the Chapter:**

> Bucky’s never actually been free. While Bucky is discovering what freedom is like, Tony is learning everything his mate likes. Fleeing south, Tony eventually brings Bucky home...

**Notes for the Chapter:**

> The final chapter of Slack Water...  
> for K2: Reunion
> 
> And again, more arts! Monobuu and I should just team up all the time, don't you think?

There was the sea.

Bucky had dragged the tiny tank down a bumpy path, much less smooth than the interior of Hydra’s cavern. He had to stop more frequently to rest; pushing the tank, or pulling it, both were equally exhausting. And the little rocks that made up the path were painful against his skin. It wasn’t far, he hoped. He scouted ahead a few times, although he tried not to get out of sight; Tony got anxious if he couldn’t see where Bucky was.

But he could hear the tide crashing against the beach, somewhere.

He only hoped he was going in the right direction.

The sun was hot, and the water in Tony’s tank was getting warmer. Uncomfortable. And Tony was starting to have trouble breathing. There just wasn’t that much oxygen left. Damn Hydra. But if they died now, so close to their goal, at least they would die free.

Further, and the rocky path gave way to thick plant material. It was smoother, and the tank rolled easier. Below them, low water rushed under it, not deep enough for Tony, and too far away to get to.

Finally, Bucky reached the end of the long wooden thing, a projected, manthings built path over the sea. The water was below them, several manlengths down.

_Tony. I’m going to push you in. Try to dive shallow. I don’t know how deep the water is._

Tony managed a weak nod.

Bucky worked the tank all the way to the edge of the wooden path and shoved as hard as he could, rocking the tank back and forth. Water spilled out of both sides as Tony sloshed back and forth inside.

The whole thing tipped and Tony hit the wooden path. He flopped a few times, back bowing as he struggled to move in the strange, waterless world, and then, _splash_ , over the side.

Bucky peered cautiously over the side, looking down into the water. He didn’t see Tony. The white froth crashed against the pillars holding up the wooden path.

Bucky skittered to the edge, then down the side to the water.

He paused at the very surface.

He’d never actually been in the ocean, not that he remembered. He knew he came from there, but Bucky was tank-raised. He’d always been in Hydra’s waters. He hesitated, then… _Tony._

Tony was waiting for him, near the bottom, tucked against one of the wooden pillars, just breathing.

The water was cool. Fresh and full of oxygen. There were other, living things. Clusters of mollusks on the wooden pillars. A bed of clams.

Bucky wrapped one arm around his mate. He told himself he wasn’t frightened. They were free. They were free of Hydra, and they could go anywhere they wanted. Well, Tony could. Bucky still had the arm, attached to him. Marked by Hydra. He would always be one of them. Not a free mer. Not… worthy.

Tony broke open a few of the mollusks, teasing the morsel out of its casing. _Food. Eat?_

_We shouldn’t stay here long. They might come looking for us._

Tony shoved several pieces of mollusk and clam into his mouth, chewing hastily. _Yeah. I don’t… I need to get my bearings._

Bucky wasn’t even sure he knew what that meant.

_Come on. This way._

Bucky followed.

The water grew deeper. Colder. Blacker. Bucky kept close to his mate.

There were more living things in the waters than Bucky had ever seen before. Fish and crustaceans. A pod of squeaky dolphins swam by them, playing in the water. Tony kept them low in the water and they moved slowly, with Tony darting from clusters of plants to sunken manthings, always looking around.

_What are you doing?_

_There are sharks, sometimes._

Bucky didn’t know what a shark was.

Whenever Bucky asked where they were going, Tony just answered south. Or something home. At least Tony had a home, Bucky guessed. Even if Bucky had no idea what or where that was. They passed a school of mers at one point, and Tony stopped to chat with them, Bucky hanging back shyly.

The water got warmer again, cleaner.

Tony was moving faster now, well fed and with fresh water surrounding them all the time, he was stronger.

They found a small cavern, enough room for them both, and a wide rock that Bucky could pull across the entrance. It was nice. Safe. They stayed a few days. Tony hunted, using his electrical pulses to stun almost an entire school of fish. Some of them swam away, but the rest of them, Bucky scurried around to grab hold of, before they floated, dead, to the surface.

It was nice.

In the dark safety of their cavern, Bucky discovered other nice things.

He discovered that Tony was honing his skill at kisses. And that there were other things they could do to each other that were pleasurable.

Tony slid his mouth along Bucky’s body, testing his reactions, seeing what felt best. There were places that Bucky liked Tony’s mouth. On his ears, especially when Tony would nip along the shell. Down the length of Bucky’s neck, which made Bucky lean his head back as far as he could, to expose his throat. Tony would lick and taste Bucky’s chest. Along the divisial line, between his upper body and that of his lower half, where pale flesh gave way to red skin.

And then there were places on Bucky’s body where Bucky _loved_ Tony’s mouth.

Tony found Bucky’s mating arm, the third right, with its sensitive packets, and touched them with his mouth. It was unbearable and wonderful at the same time. Bucky’s other arms pulled ‘round his mate, drew him closer. Each sucker mouth clamped on to Tony’s skin, a little kiss, a hundred little kisses.

_I have you, darling._

Bucky writhed in Tony’s embrace as Tony licked and fondled the length of Bucky’s mating arm, stimulating and teasing and tormenting it all at once. Sensation zinged along all his nerves.

 _What do I… how do--_ Bucky and Tony were different species, Tony didn’t have a mating arm, not that Bucky had been able to see or discover. Bucky didn’t know how to please his mate.  

 _You are pleasing me._ Tony gently pulled Bucky’s mating arm out of his mouth, nipped at the very tip. He swam up, rubbing himself against Bucky’s body. Took Bucky’s upper arm, one finger. _Press, here._ He opened his mouth, indicated the specialized glands inside his mouth. _Here. And here. Every time you give me kisses, it pleases me._

Bucky poked gingerly inside Tony’s mouth. Tony arched into it, his spine curving beautifully.

_Yes like, oh. Oh, Neptune, sweet--_

And then it was push and pull, Bucky holding onto Tony with as many arms as he could wrap around the daggerfish. Tony, open mouthed and making sweet sounds in the water, licking and biting and stroking at Bucky’s mating arm.

Tension shot between them, grew, and grew, until Bucky didn’t know what was happening. Everything was light and soft and warm, and he felt so, so good.

_Tony! Tony!_

There was a rhythm in it, an intimacy like Bucky had never known. Losing himself in the body of another. Touching, and stroking and-- _Oh, Tony!_

He tightened his grip until there was no room at all between Tony and himself, until every inch of his flesh was pressed against Tony, fingers and mating arm in Tony’s mouth, and he swelled and ached and…

_Bucky!_

The ocean boiled around him. Everything, everything was light and pleasure and sweetness. Bucky felt like his very essence was pulling away from his body, that he was glowing like the sun, that… oh, Neptune, that was good. It was go, so good.

Tony was shivering all over, clinging and tense and then he cried out.

_I’ve got you._

_Yes, yes you do._ Tony gazed at him fondly through lowered eyelids. _You have me, and you will always have me._

The days passed, hunting and securing their home. The nights passed, locking in each other’s embrace.

Bucky was happy, satisfied. Octomers were solitary creatures. Even a mate was more than Bucky usually had. He was happy. Content. But Tony was missing the company of others. Bucky was good, Tony insisted, but sometimes, Bucky still found his mate staring south, like there was somewhere else he wanted to be.

They were hunting one day, the waters warm and calm, and then a creature approached.

Bucky had never seen anything like it. Both dark and shiny at the same time, hundreds of tendrils descending from its body, with a full, purple mantle and beautiful, rippling skin. A jellyfish of some sort, Bucky thought. He knew the creature; Hydra had tested him against other marine life, sometimes, drove them to combat and killing. Dumb, witless animals, or sometimes other men. Bucky was a survivor. He pulled Tony behind him, getting ready to defend his mate.

Tony was squirming around, trying to see past Bucky.

_Tones!_

_Oh_! Tony was staring at the jellyfish, a thick, poisonous, dangerous creature, and Tony dodged Bucky’s protective embrace and swam at it, fast as anything.

 _Tony! Tony, wait, no._ Bucky tried to catch his mate, but he wasn’t fast enough, and the jellyfish swarmed over him. The tendrils that could catch and sting, poison and kill, wrapped around Tony.

 _Next time, next time, you stay with me._ The man-o-war was petting Tony, as if reassuring himself that Tony was okay, that he was alive, that he was safe.

Bucky hovered, worried.

 _Bucky_. Tony reached out through the sea of tendrils for Bucky’s hand. _This is Rhodey, my best friend. How did… how did you find me? Us?_

 _I ain’t ever going to stop looking for you, not ever._ Rhodey’s hands were tight on Tony’s shoulders, his whole face relieved, and Tony was hugging the man-o’-war with all his might.

Tony smiled, his whole face crinkling up with joy. _Rhodey, this is Bucky. My mate._

Rhodey looked over Tony’s shoulder at Bucky, brown eyes assessing, everything about the man-o’-war shrieking danger, hostility. Defending Tony from _Bucky_? Bucky wouldn’t harm his mate. Bucky scowled, crossing his arms over his chest.

Rhodey shook his head. _Tones, why don’t you_ ever _do things th’ easy way?_

 _Where would the fun in that be?_ Tony protested. _Stop being such a grump, sourpatch. It’s all good. Everything’s good here. I’m home._

Bucky squeezed in, evading the spiny, stinging tendrils, until he could reach Tony’s hand. Twined their fingers together. He wasn’t sure what a best friend was, or why Tony had one, but this was part of his mate’s life, and he was staying with his mate. No matter what.

Tony leaned over and kissed him, in front of his friend, like their mating was already accepted, acknowledged. Bucky humming into it, taking comfort. And if he was cautiously checking every inch of Tony’s skin, making sure Rhodey hadn’t hurt him or stung him, well, that was just concern. Tony didn’t seem to mind.

 _Welcome home, Tones._  

**Notes for the Chapter:**

> Electric Eels mate by the boy eel spitting up a nest for the female to lay eggs in. I took some liberties (and more than a few, since electric eels are actually fresh water fish) and basically, Tony orgasms through oral stimulation. So, all those kisses? Yeah, Bucky was getting Very Fresh, as far as Tony was concerned!

**Author's Note:**

> Inspired by this art [ by @beir](http://beir.tumblr.com/post/174053708188/moni12m-replied-to-your-photo-let-me-help-you)


End file.
